The present invention relates to a semiconductor device and a method for fabricating the same, more specifically a semiconductor device including a sidewall insulation film formed on the side wall of a gate electrode and a method for fabricating the same.
As the integration and the speed of semiconductor devices are increased, the nanonization of device structures, as of MOS transistors, etc., is rapidly progressing. Especially gate electrodes are formed not only in nanonized sizes but also with a small gap with respect to adjacent gate electrodes.
The background arts of the present invention are disclosed in e.g., Japanese published unexamined patent application No. Hei 07-307465 (1995).
However, when the gap between adjacent gate electrodes is small, the gap is often filled with an insulation film forming the sidewall insulation film. This makes difficult the ion implantation for forming impurity diffused regions for forming source/drain diffused layers.
On the other hand, too thin sidewall insulation film to be formed makes the distance between the source diffused layer and the drain diffused layer too small, which deteriorates the characteristics of MOS transistors and furthermore makes the operation itself difficult.